From patchwork Tue Jan 28 15:17:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kevin Wolf X-Patchwork-Id: 1230414 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256 header.s=mimecast20190719 header.b=aftfcSVC; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 486Vd74Dsnz9sRW for ; Wed, 29 Jan 2020 02:18:49 +1100 (AEDT) Received: from localhost ([::1]:60434 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iwSda-0004Me-Ka for incoming@patchwork.ozlabs.org; Tue, 28 Jan 2020 10:18:46 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:33275) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iwSdD-0004ML-7T for qemu-devel@nongnu.org; Tue, 28 Jan 2020 10:18:24 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iwSdA-0003dr-Ts for qemu-devel@nongnu.org; Tue, 28 Jan 2020 10:18:22 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:48365 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iwSdA-0003d1-Jv for qemu-devel@nongnu.org; Tue, 28 Jan 2020 10:18:20 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580224699; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=zjC0WJacR+CukA9vSHIb1ajtg0i3wEuf7gyGAcSjcxY=; b=aftfcSVCIwDfcjrmEYP0+2sPwFVeY4AeG2PfETe+3UjthjXXZXrH0CdRFQqvUT3hKw3DKW gUPfmZxVP4kppPqIuPpIQBG7Wx28xAyP6KLSf5ZxqdE7Qb6DAK9kEk35VhjUQLvr4pf7S8 1jeC85g7/rCqtqVNPAu4tcqY3JlnWAk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-298-OfeGEKmGNI6C074GOxKJKQ-1; Tue, 28 Jan 2020 10:18:17 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id A8CF21019129; Tue, 28 Jan 2020 15:18:16 +0000 (UTC) Received: from linux.fritz.box.com (ovpn-117-106.ams2.redhat.com [10.36.117.106]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3116489D2E; Tue, 28 Jan 2020 15:18:14 +0000 (UTC) From: Kevin Wolf To: qemu-block@nongnu.org Subject: [PATCH 2/2] mirror: Don't let an operation wait for itself Date: Tue, 28 Jan 2020 16:17:55 +0100 Message-Id: <20200128151755.25162-3-kwolf@redhat.com> In-Reply-To: <20200128151755.25162-1-kwolf@redhat.com> References: <20200128151755.25162-1-kwolf@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-MC-Unique: OfeGEKmGNI6C074GOxKJKQ-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, jsnow@redhat.com, qemu-devel@nongnu.org, mreitz@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" mirror_wait_for_free_in_flight_slot() just picks a random operation to wait for. However, when mirror_co_read() waits for free slots, its MirrorOp is already in s->ops_in_flight, so if not enough slots are immediately available, an operation can end up waiting for itself to complete, which results in a hang. Fix this by passing the current MirrorOp and skipping this operation when picking an operation to wait for. Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1794692 Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake --- block/mirror.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) diff --git a/block/mirror.c b/block/mirror.c index 8959e4255f..cacbc70014 100644 --- a/block/mirror.c +++ b/block/mirror.c @@ -283,11 +283,14 @@ static int mirror_cow_align(MirrorBlockJob *s, int64_t *offset, } static inline void coroutine_fn -mirror_wait_for_any_operation(MirrorBlockJob *s, bool active) +mirror_wait_for_any_operation(MirrorBlockJob *s, MirrorOp *self, bool active) { MirrorOp *op; QTAILQ_FOREACH(op, &s->ops_in_flight, next) { + if (self == op) { + continue; + } /* Do not wait on pseudo ops, because it may in turn wait on * some other operation to start, which may in fact be the * caller of this function. Since there is only one pseudo op @@ -302,10 +305,10 @@ mirror_wait_for_any_operation(MirrorBlockJob *s, bool active) } static inline void coroutine_fn -mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s) +mirror_wait_for_free_in_flight_slot(MirrorBlockJob *s, MirrorOp *self) { /* Only non-active operations use up in-flight slots */ - mirror_wait_for_any_operation(s, false); + mirror_wait_for_any_operation(s, self, false); } /* Perform a mirror copy operation. @@ -348,7 +351,7 @@ static void coroutine_fn mirror_co_read(void *opaque) while (s->buf_free_count < nb_chunks) { trace_mirror_yield_in_flight(s, op->offset, s->in_flight); - mirror_wait_for_free_in_flight_slot(s); + mirror_wait_for_free_in_flight_slot(s, op); } /* Now make a QEMUIOVector taking enough granularity-sized chunks @@ -555,7 +558,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s) while (s->in_flight >= MAX_IN_FLIGHT) { trace_mirror_yield_in_flight(s, offset, s->in_flight); - mirror_wait_for_free_in_flight_slot(s); + mirror_wait_for_free_in_flight_slot(s, pseudo_op); } if (s->ret < 0) { @@ -609,7 +612,7 @@ static void mirror_free_init(MirrorBlockJob *s) static void coroutine_fn mirror_wait_for_all_io(MirrorBlockJob *s) { while (s->in_flight > 0) { - mirror_wait_for_free_in_flight_slot(s); + mirror_wait_for_free_in_flight_slot(s, NULL); } } @@ -794,7 +797,7 @@ static int coroutine_fn mirror_dirty_init(MirrorBlockJob *s) if (s->in_flight >= MAX_IN_FLIGHT) { trace_mirror_yield(s, UINT64_MAX, s->buf_free_count, s->in_flight); - mirror_wait_for_free_in_flight_slot(s); + mirror_wait_for_free_in_flight_slot(s, NULL); continue; } @@ -947,7 +950,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp) /* Do not start passive operations while there are active * writes in progress */ while (s->in_active_write_counter) { - mirror_wait_for_any_operation(s, true); + mirror_wait_for_any_operation(s, NULL, true); } if (s->ret < 0) { @@ -973,7 +976,7 @@ static int coroutine_fn mirror_run(Job *job, Error **errp) if (s->in_flight >= MAX_IN_FLIGHT || s->buf_free_count == 0 || (cnt == 0 && s->in_flight > 0)) { trace_mirror_yield(s, cnt, s->buf_free_count, s->in_flight); - mirror_wait_for_free_in_flight_slot(s); + mirror_wait_for_free_in_flight_slot(s, NULL); continue; } else if (cnt != 0) { delay_ns = mirror_iteration(s);